This invention relates to an interconnectable structural module, particularly, but not exclusively, for use as a drainage module.
The control and flow of surface water, such as rain water or storm water, is important in preventing the build up of surface water adjacent foundations of buildings or other structures, and in other areas such as on playing fields, golf courses, landscaped decks, gardens and the like. In densely built up areas, the increased surface run-off of storm and rain water has resulted in massive storm water channels being built to cope with the quantities of run-off water. However, these impervious drainage systems take up large areas of land and are not only an eyesore, but are expensive to build and maintain. Further, they are often polluted by sedimentation and organic rubbish. Storm water channels often smell offensive and can turn into major breeding grounds for pests and diseases.
One solution to this problem, has resulted in the invention of subsoil modular drainage systems such as the xe2x80x9cNORDRAINxe2x80x9d(trademark) subsoil modular drainage system (trade mark of Nortec Geo-Systems (S) Pte Limited of Scotts Road. #05-05 Singapore). The NORDRAIN system comprises a rigid cell including a first and a second substantially parallel planar member, each of which defines an ordered array of circular apertures with a series of columns which are disposed substantially normally to the two parallel surfaces retaining the two members in a fixed spaced relationship from each other. The circular apertures in the first and second planar members are out of register such that the centre of an aperture in the first member is generally opposed to a solid area of the second member disposed between four adjacent circular apertures in the second member.
Such sub-soil modular drainage systems create a permanent void between a building structure and the soil profile and thus allow easy passage of excess subterranean waters to designated outlets. They are also used in drainage applications for playing fields, golf courses and the like and for making underground storage tanks when they are assembled in a box structure and covered in geotextile.
FIG. 1 of the attached drawings illustrates the use of a NORDRAIN sub soil modular drainage system 3 against a retaining wall 1 to provide relief from hydrostatic pressure on that wall by channelling excess waters to an appropriate outlet. A waterproof membrane 2 is disposed between one face of the NORDRAIN module and the wall 1, and the other face of the NORDRAIN module is covered in a geotextile 4.
Such modules tend to be made to a particular, relatively small, size typically about 340 longxc3x97340 widexc3x9730 mm deep and the modules are joined together to create larger drainage structures. Although the NORDRAIN and other similar subsoil modular drainage systems work well, sometimes problems arise in assembling the modules into an appropriately sized composite module sized for a particular application. This is often done using separate clips. Problems arise in particular where the modules are being used against a retaining wall in a generally vertical orientation.
It is an object of the present invention to provide an improved drainage module with improved means for assembling the drainage modules together.
According to the present invention, there is provided a structural module comprising:
a first and a second substantially parallel generally planar member retained in a fixed spaced relationship from each other by a plurality of spacers extending between the first and second planar members, the module having side edges extending between perimeters of the first and second planar members and wherein each planar member defines an ordered array of apertures;
male interlocking means which are integral with the module projecting from at least a first one of the side edges;
female interlocking means defined in at least a second of the side edges adapted to receive a male interlocking means so that two modules can be secured together in side edge to side edge relation;
characterised in that the size and configuration of the male locking means relative to the size and configuration of the apertures, is such that a first module may also be inter-engaged with a second module, with the first module oriented generally normally to the second module with a side edge of the first module abutting a planar member of the second module and with each male locking member defined along said side edge of the first member extending into one of the apertures defined in one of the planar members in a close or interference type fit with the aperture.
In a preferred embodiment, the female locking means comprise elongate slots defined between the ends of two walls, forming part of the side edges. The slots have an open end and a closed end. The male locking means may comprise two arms which are generally L shaped in cross section. When two modules are butt joined and interlocked in end to end relation the ends of the arms engage, behind the walls defining the slots.
The apertures are preferably generally circular.
It is preferred that the area of the apertures comprises at least 50% of the surface area of the first and second planar members.
It is preferred that the apertures in the planar members are arranged substantially regularly and uniformly.
In one particularly preferred embodiment, the male locking means equidistantly spaced along a first two adjacent sides of the module; the arrangement of male locking means along each adjacent side is asymmetric (i.e. offset). A series of gaps are disposed between each pair of male locking means. The female locking means are also equidistantly and asymmetrically spaced along the other two sides of the module. A series of gaps are also disposed between each pair of female locking means. The gaps are wider than the male members. The arrangement of male locking means, female locking means and gaps is such that when a module is abutted end to end with another module, with the tops of both modules facing up (or both facing down) the modules will interlock. In this arrangement the modules are butt joined and also interlocked. However, if one of the modules is turned around through 180xc2x0 so that the sides having male interlocking means face each other, or if one of the modules is turned upside down relative to the other because of the asymmetry of the arrangement of the male locking means, the male locking means simply locate in some of the gaps and do not interlock the modules together. In this arrangement the modules are butt joined but not interlocked. Modules may also be butted and not interlocked by positioning together, sides having female interlocking means. The invention has the advantage over existing products in that it is not necessary to carefully align modules or clip them together.
In addition to use as a drainage cell, other possible uses for the module include, a drainage layer, a protection layer, a core for covered/uncovered panels, and when assembled as a box structure, as retention/detention tanks, table supports and the like. In addition, the modules may be used as channels/ducts for the flow of liquids, gases, solids having a small particle size, as a protection layer, as a separator, a panel for table tops, or as panels for doors or room partitions, exhibition stands, supports for other structures, or the like. Other uses which benefit from the modules manner of interlocking, fluid permeation characteristics and/or shear, compression and torsional strengths may be envisaged.
The module may be injection moulded in PP (polypropylene) HDPE (high density polyethylene) or LPDE (low density polyethylene). However, any other suitable materials which can be moulded or cast, may be used, including aluminum and rubber.
In a related aspect, to the present invention also encompasses the use of the nodule of the present invention, to make drainage piping or underground tanks by assembling and interlocking the modules into boxes or pipes and covering them with geotextile or the like.